An LNG ship cooling and inerting system and control method

Abstract

An LNG ship cooling and inerting system and control method, which relates to the field of LNG ships, cooperates with heat exchangers, cargo tanks and terminal equipment in the ship's hull. The terminal equipment is connected to the heat exchanger. The system includes a spraying system and a vaporization system; the vaporization system includes a liquid nitrogen tank and a vaporizer. The liquefied nitrogen in the liquid nitrogen tank is vaporized by the vaporizer and then transported to the cargo tank for inerting; the spraying system includes an external water source and spraying pipe fittings. The water from the external water source flows into the heat exchanger to cool the terminal equipment, and after the cooling water is heated, it is sprayed from the spraying pipe fittings to the vaporizer; the present invention uses the heat energy absorbed by the temporary cooling water to cool some ship equipment to compensate for the insufficient heat absorption of the fins of the liquid nitrogen vaporizer, realizing the exchange and utilization of cold and hot energy and saving energy.

Description

Technical Field

[0001] The present invention relates to the field of LNG ships, and more specifically, to an LNG ship cooling and inerting system and a control method therefor. Background Art

[0002] During the repair of liquid cargo ships such as LNG, LPG, LNH3, and methanol when they are docked, the original cooling system on the ship must be deactivated or partially deactivated. However, some equipment on the ship still requires the cooling system to ensure operation. Therefore, temporary cooling facilities are needed to provide circulating cooling water. Additionally, in winter, the environmental temperature is relatively low, and for the liquid nitrogen vaporizer used to supply inerting gas for the liquid cargo tanks on the ship, the vaporization effect is poor due to insufficient heat exchange. In the prior art, temporary cooling facilities are required to separately cool the facilities on the docked liquid cargo ship. However, the cold energy during the vaporization of liquid nitrogen is directly discharged, and heat energy is required to heat the outside of the vaporizer fins to remove fog and frost and improve the vaporization efficiency. The exchange of temporary cooling water source and the cold energy outside the fins during the vaporization process cannot be achieved, resulting in waste. Summary of the Invention

[0003] The present invention aims to overcome at least one defect of the above prior art, and provides an LNG ship cooling and inerting system and a control method therefor, which utilize the heat energy absorbed by the temporary cooling water after cooling some equipment on the ship to compensate for the insufficient heat absorption of the fins of the liquid nitrogen vaporizer, realizing the exchange and utilization of cold and hot energies and saving energy.

[0004] Another technical solution provided by the present invention is an LNG ship cooling and inerting system and a control method therefor, which cooperate with a heat exchanger, a liquid cargo tank, and terminal equipment inside the ship. The terminal equipment is connected to the heat exchanger. The system includes a spraying system and a vaporization system. The vaporization system includes a liquid nitrogen tank and a vaporizer. The liquefied nitrogen in the liquid nitrogen tank is vaporized by the vaporizer and then transported to the liquid cargo tank for inerting through a low-temperature hose. The spraying system includes an external water source and spraying pipe fittings. The water of the external water source flows into the heat exchanger to cool the terminal equipment. After the cooling water is heated, it forms spraying water and sprays onto the vaporizer from the spraying pipe fittings. After the spraying water exchanges heat with the vaporizer, it is collected in the external water source, and the circulation of the external water source is realized by directly collecting the water passing through the vaporizer.

[0005] When the LNG ship is at the shore for repair, the original cooling system on the ship must be deactivated or partially deactivated. Other terminal equipment on the ship requires a cooling system to ensure operation. The common method is to use temporary cooling facilities to provide circulating cooling water. In this technical solution, the external water source is set on the shore, which can be a water tank or a water storage tank, and is connected to the heat exchanger through a pipeline. The terminal equipment inside the ship is also connected to the heat exchanger. When the external normal-temperature water source passes through the heat exchanger, it cools down the terminal equipment. At the same time, the temperature of the normal-temperature water rises and flows through the pipeline to the spray pipe fittings and sprays out from the spray pipe fittings. In addition, before the LNG ship is loaded, the cargo tank needs to be inerted first. The inerting process is as follows: The liquid nitrogen in the liquid nitrogen tank passes through the vaporizer, and the vaporizer vaporizes the liquid nitrogen and transports it to the cargo tank in the LNG ship for inerting. During the vaporization of the liquid nitrogen, heat from the surrounding environment is absorbed by the fins, resulting in a large amount of white fog around the vaporizer, and even frost or ice formation on the vaporizer itself. In this solution, the external water heated up in the spray pipe fittings is sprayed out from above or inside the vaporizer to dilute the white fog around the vaporizer and eliminate the frost or ice. Part of the external water is directly sprayed on the fins of the vaporizer to achieve the effect of removing frost and ice. During the implementation of this solution, the heat energy generated by the external water source cooling some equipment on the ship is used to compensate the liquid nitrogen vaporizer, realizing the exchange and utilization of cold and heat energy, increasing the working efficiency of the vaporizer and saving energy. Secondly, the water sprayed onto the vaporizer in this solution can finally be collected and input into the external water source, or a water tank can be placed at the bottom of the vaporizer to directly collect the water passing through the vaporizer, realizing the recycling of the external water source. Preferably, the external water source in this solution can be set at the bottom of the vaporizer, so that the sprayed water freely falls after heat exchange with the vaporizer and is collected in the external water source. The external water source is placed at the bottom of the vaporizer to directly collect the water passing through the vaporizer, realizing the direct recycling of the external water source and reducing the use of pipeline components. In addition, the cooling and inerting system in this solution is simple and practical, with a compact structure, and is especially suitable for mobile use. In the actual application process, the external water source and the vaporizer can be set as an integrated structure up and down. According to the required water volume for ship cooling and the required nitrogen volume for inerting, multiple groups of external water sources and vaporizers can be configured to access multiple heat exchangers at different positions on the ship for cooling or inert multiple cargo tanks.

[0006] Further, there are multiple spray pipe fittings, and each spray pipe fitting includes multiple spray pipes. Multiple nozzles are provided on each of the multiple spray pipes; the vaporizer includes multiple fins; the multiple fins and the multiple spray pipes are distributed at intervals; the multiple nozzles are evenly arranged on the pipe wall of the spray pipe, and a pipe plug is provided at the bottom of the spray pipe.

[0007] In this solution, a finned vaporizer can be used, which includes a number of regularly distributed fins. A plurality of nozzles are arranged at intervals between the fins, so that at least part of the fins and the nozzles are distributed at intervals, making the heat exchange more uniform and rapid, and improving the working efficiency of the vaporizer. In addition, a plurality of nozzle rings are arranged at intervals in the axial direction of the nozzle. Each nozzle ring is provided with a plurality of nozzles at intervals in the circumferential direction of the nozzle, ensuring that the nozzle sprays water onto the fins evenly from top to bottom. The purpose of setting the pipe plug is to control the external water to spray only from the pipe wall of the nozzle and not leak from the bottom, so that the external water flows from top to bottom and fully continues the heat exchange.

[0008] Further, there are 4 fins in the circumferential direction of each nozzle. The number of nozzles is adjusted according to the requirement of the inerting nitrogen quantity, but at least ensure that each nozzle is located at the center of 4 fins. Preferably, the 4 fins are distributed in a square, and the nozzle is located at the centroid of the square to ensure the same heat exchange efficiency with each fin. In this solution, when it is necessary to further improve the heat exchange efficiency, it is divided into 3 groups according to the liquid nitrogen flow direction, and the water spraying is triggered in sequence according to the temperature; when it is necessary to save the number of nozzles, the number of nozzles for water spraying can be controlled individually for flexible adjustment.

[0009] Further, a plurality of the fins are distributed in a rectangular shape of m rows * n columns. The relationship between a plurality of the nozzles and a plurality of the fins is as follows: a plurality of the nozzles are distributed in a rectangular shape of (m - 1) rows * (n - 1) columns. There are 4 fins in the circumferential direction of each nozzle, where m ≥ 4 and n ≥ 4. That is to say, in this solution, nozzles are arranged between every two adjacent rows of fins and every two adjacent columns of fins, so that there is a nozzle at the centroid of each fin block distributed in a 1 * 1 rectangle. Such a setting can make the heat exchange efficiency between the sprayed water and the vaporizer reach the highest, and make full use of each nozzle to spray water in the circumferential direction.

[0010] Further, a plurality of the fins are distributed in a rectangular shape of m rows * n columns. The relationship between a plurality of the nozzles and a plurality of the fins is as follows: a plurality of the nozzles are distributed in a rectangular shape of (m / 2) rows * (n / 2) columns. There are 4 fins in the circumferential direction of each nozzle, where m ≥ 6 and n ≥ 6; when m or n is odd, (m / 2) rows or (n / 2) columns are rounded up. That is to say, in this solution, every two adjacent rows and every two adjacent columns of fins are taken as a group of fins, and a nozzle is arranged in the middle of the group of fins, so that 4 fins and 1 nozzle in the center of them are used as a unit group, and the distribution rules of the spray pipe fittings and the vaporizer are composed of one or more such unit groups. Such a setting enables 1 nozzle to spray water on 4 fins at the same time, and each fin has and only has one nozzle for water spraying, while ensuring the heat exchange efficiency between the sprayed water and the vaporizer, minimizing the number of nozzles, saving costs, and simplifying the components of this system.

[0011] Further, the nozzles on the nozzle pipe are distributed in multiple layers axially; the nozzles in the same layer are provided with a plurality of nozzles distributed circumferentially, preferably arranged in an equal-arc annular shape; the opening position of the nozzle and its water spraying direction are directly opposite to the center of the fin. The purpose of such a setting is to enable the sprayed water from the nozzle to directly reach the fin, reduce the heat energy loss of the sprayed water, directly act on the fin, and improve the heat exchange efficiency.

[0012] Further, a nozzle pipes are arranged along the flow direction of liquid nitrogen entering the vaporizer, and the number of nozzles on the a nozzle pipes shows a decreasing trend along the flow direction of liquid nitrogen; where a≥3. Along the flow direction of liquid nitrogen, the energy of the vaporizer decays, and under the condition of the same water temperature of the sprayed water, the required water volume gradually decreases. In order to improve the recycling rate of the sprayed water, the number of nozzles shows a decreasing trend along the flow direction of liquid nitrogen; preferably, it decreases in an arithmetic progression. In this technical solution, it can be achieved by gradually shortening the length of the nozzle pipe, and the nozzle spacing between adjacent two layers on each nozzle pipe is the same. The fin temperature of the liquid nitrogen vaporizer is the lowest near the inlet along the flow direction of liquid nitrogen, and the required heat exchange amount is the largest. The fin temperature near the outlet is relatively high, and the required heat exchange amount is relatively small. Therefore, the number of spray pipe fittings and the spray water volume can be gradually decreased in sequence along the flow direction of liquid nitrogen to improve the spray water heat exchange efficiency.

[0013] Further, the a nozzle pipes are divided into 3 groups according to the flow direction of liquid nitrogen, and are sequentially defined as group A1, group A2, and group A3. The number of each group is a1, a2, and a3 respectively, where a1 = a3 = a / 3, a = a1 + a2 + a3 (when a / 3 is not an integer, it is rounded down); such a setting is to reduce the amount of sprayed water while ensuring the heat exchange efficiency of the sprayed water for the fins. Among them: Group A1 is provided with a first nozzle pipe main valve, each nozzle pipe is provided with 6 layers of nozzles, and 4 nozzles in each layer; Group A2 is provided with a second nozzle pipe main valve, each nozzle pipe is provided with 4 layers of nozzles, and 4 nozzles in each layer; Group A3 is provided with a third nozzle pipe main valve, each nozzle pipe is provided with 2 layers of nozzles, and 4 nozzles in each layer.

[0014] Further, the spraying system further includes a water pump for pumping out the water from an external water source, and a water outlet pipe manifold connected to the external water source. The water outlet pipe manifold is provided with a plurality of water outlet branches, and one or more of the water outlet branches flow into the heat exchanger; the spraying system further includes a water return pipe manifold for conveying water to the spray pipe fittings. The water return pipe manifold is provided with a plurality of water return branches, and one or more of the water return branches are connected to the heat exchanger and then flow into the water return pipe manifold; the spraying system further includes a first valve arranged on the water outlet branch, a second valve arranged on the water return branch, a temperature sensor, and a pressure gauge; temperature sensors and pressure gauges are arranged on both the water outlet pipe manifold and the water return pipe manifold.

[0015] In this solution, the water pump can be set to only pump out the external water source, or can be set on the pipeline between the external water source and the heat exchanger or the outlet pipe manifold, and is used to pump out the external water source and then transport it into the heat exchanger or the outlet pipe manifold. In order to better control the water pumping time, a pipeline valve can be set on the pipeline between the external water source and the outlet pipe manifold; the purpose of setting multiple water outlet branches is to control the water volume flowing into the heat exchanger by controlling the on-off of a certain or several water outlet branches, and accurately control the flow rate of the cooling water according to the required water volume for ship cooling and the required nitrogen volume for inerting; setting the first valve or the second valve is to control the opening and closing of each water outlet branch or the water return branch, which is convenient to operate. The water temperature of the external water after fin heat exchange through the vaporizer is monitored by a temperature sensor and a pressure gauge, and whether to trigger the first valve or the second valve, or trigger several first valves or second valves is determined according to the temperature and pressure values to adjust the water volume and water temperature flowing into the heat exchanger; secondly, when multiple vaporizers are configured to be connected to multiple heat exchangers at different positions on the ship for cooling, the water outlet branches can be directly connected to different heat exchangers, which is simple to operate and highly flexible.

[0016] Furthermore, the system further includes multiple water outlet spare interfaces arranged on the outlet pipe manifold and multiple water return spare interfaces arranged on the water return pipe manifold; it also includes multiple external water sources and vaporizers with the same quantity. One vaporizer and one external water source are arranged vertically to form a circulation component. Each external water source is connected to the outlet pipe manifold through a water outlet spare interface, and each vaporizer is connected to the water return pipe manifold through a water return spare interface. Pipeline valves are provided on the pipelines between the external water sources and the outlet pipe manifold. That is to say, multiple said vaporizers are connected in parallel. In this technical solution, multiple circulation components are particularly suitable for mobile use. According to the number of terminal equipment to be cooled on the ship and the amount of liquid nitrogen required for inerting, multiple groups of circulation components are configured to be connected to multiple heat exchangers at different positions on the ship for cooling or to inert multiple liquid cargo tanks, and the assembly is simple and the effect is good.

[0017] The present invention also provides another technical solution: a control method for an LNG ship cooling and inerting system. The system further includes a control panel, and the control panel is signal-connected to the temperature sensor on the outlet pipe manifold; when the temperature T of the outlet pipe manifold reaches the threshold value t1, the H mode is triggered, and the nozzles of group A1 are controlled to open through the first nozzle main valve for spraying; when the temperature T of the outlet pipe manifold reaches the threshold value t2, the HH mode is triggered, and the nozzles of group A2 are controlled to open through the second nozzle main valve for spraying; when the temperature T of the outlet pipe manifold reaches the threshold value t3, the HHH mode is triggered, and the nozzles of group A3 are controlled to open through the third nozzle main valve for spraying.

[0018] In this technical solution, a water pump transports external water into the ship for circulating and cooling the heat exchanger. The heat exchanger is used to cool the terminal equipment on the ship. The temperature of the water returning from the outlet of the heat exchanger rises, and after passing through the fins of the spray vaporizer, it is cooled and the temperature drops. The temperature sensor sets a threshold in advance to trigger the temperature mode. Three levels of modes are set, namely H, HH, and HHH levels of modes, and the corresponding temperature thresholds are t1, t2, and t3 respectively. The efficiency of heat exchange with the vaporizer is controlled by controlling the number of nozzles participating in this system, realizing more precise control.

[0019] Further, 40°C > t3 > t2 > t1 > 10°C.

[0020] Further, the system further includes multiple outlet standby interfaces arranged on the outlet pipe manifold and multiple return water standby interfaces arranged on the return water pipe manifold; the system further includes multiple heat exchangers connected in parallel and multiple vaporizers connected in parallel; the control panel is also connected to the temperature sensing signal on the return water pipe manifold; a low-temperature mode threshold t4 and a high-temperature mode threshold t5 are set; when the temperature T of the temperature sensor reaches the low-temperature mode threshold t4, the control panel controls the activation of multiple outlet branches and return water branches, and connects multiple heat exchangers in parallel to the system; when the temperature T of the temperature sensor reaches the high-temperature mode threshold t5, the control panel controls the activation of multiple outlet standby interfaces and return water standby interfaces, and connects multiple vaporizers in parallel to the system. In this technical solution, the number of vaporizers and heat exchangers participating in this system is controlled through the return water standby interface and the outlet standby interface, and precise automated operation is achieved through the signal connection of the control panel.

[0021] Compared with the prior art, the present invention has the following effective effects: The cooling and inerting system is simple, practical, and compact, and is especially suitable for mobile use. According to the needs of the cooling water volume of the ship and the nitrogen volume for inerting, multiple sets of circulation components composed of a vaporizer and an external water source arranged vertically can be configured to access multiple heat exchangers at different positions on the ship for cooling or inert multiple liquid cargo holds; the cooling and inerting system provides circulating water for cooling the heat exchanger on the ship, and the hot return water is sprayed on the liquid nitrogen vaporizer to increase the working efficiency of the vaporizer; the nozzles on the nozzle are distributed in multiple layers, the nozzles present an annular array, and the opening position and the water spraying direction of the nozzles are directly opposite to the center of the fins, with good spraying effect; a first valve, a second valve, a temperature sensor, and a pressure gauge are provided to achieve precise control of multiple heat exchangers, multiple vaporizers, multiple liquid cargo holds, and multiple spray pipe fittings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a system diagram of the present invention.

[0023] Figure 2 It is a distribution diagram of the fins and nozzles in Embodiment 1 of the present invention.

[0024] Figure 3 This is the distribution diagram of the fin and the nozzle in Embodiment 2 of the present invention.

[0025] Figure 4 is Figure 2 or Figure 3 the sectional view of C-C in

[0026] Figure 5 This is the system diagram of Embodiment 3 of the present invention. Detailed implementation manners

[0027] The drawings of the present invention are only for illustrative purposes and should not be construed as a limitation to the present invention. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged or reduced, which do not represent the dimensions of the actual products; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0028] Embodiment 1

[0029] As Figure 1 shown, an LNG marine cooling and inerting system and a control method cooperate with a heat exchanger 11, a cargo tank 12 and terminal equipment 13 in a hull 1. One or more terminal equipment 13 are provided and need to be cooled by a cooling system to ensure operation. The terminal equipment 13 is connected to the heat exchanger 11. The system includes a spraying system and a vaporization system.

[0030] The spraying system includes an external water source 21, a water outlet manifold 23, a water return manifold 24 and a spraying assembly connected by a pipeline 4; the water outlet manifold 23 is connected to the heat exchanger 11 after being merged into the pipeline 4 through one or more water outlet branches 28, or one or more water outlet branches 28 are directly connected to the heat exchanger 11; one or more water return branches 29 are arranged at the water inlet end of the water return manifold 24. The water of the external water source flows through the heat exchanger 11 through the pipeline 4 as shown by the solid arrows in the figure and then is merged into the water return manifold 24 through the pipeline 4, or directly flows into the water return manifold 24 through one or more water return branches 29. The water flowing out of the water return manifold 24 is sprayed out through the pipeline 4 into a spraying pipe fitting.

[0031] Preferably, the spraying system further includes a water pump 22 and a pipeline valve 221 arranged on the pipeline between the external water source 21 and the water outlet manifold 23, further includes a temperature sensor 26 and a pressure gauge 27 connected to the water return manifold 24, and further includes a first valve 281 arranged on each water outlet branch 28.

[0032] Preferably, the spraying system further includes a pipeline valve 221 provided on the pipeline 4 at the water outlet end of the return water pipeline network 24, a temperature sensor 26 and a pressure gauge 27 connected to the water outlet pipeline network 23 or an external water source 21, and a second valve 291 provided on each return water branch 29.

[0033] The vaporization system includes a liquid nitrogen tank 31 and a vaporizer 32. The liquefied nitrogen in the liquid nitrogen tank 31 is vaporized by the vaporizer 32 and then transported to inert the liquid cargo hold 12. The vaporizer 32 can adopt a finned vaporizer, which includes fins 321. Each fin 321 is vertically and parallelly distributed. Each fin 321 is connected by a liquid nitrogen pipe. As shown by the hollow arrows in the figure, the liquid nitrogen in the liquid nitrogen tank 31 is vaporized by the vaporizer 32 and then transported to the liquid cargo hold 12 on the ship 1 through a cryogenic hose 134 for inerting.

[0034] Preferably, the external water source 21 is set on the shore and can be a water tank or a water storage tank, so that the external water after heating up in the spraying pipe fittings is ejected from above or inside the vaporizer 32 to dilute the white mist around the vaporizer 32. Part of the external water is directly sprayed on the vaporizer 32 to achieve the effect of removing frost. In this embodiment, the water sprayed onto the vaporizer 32 is finally collected in the external water source 21, or a water tank is placed at the bottom of the vaporizer 32 to directly collect the water passing through the vaporizer 32, realizing the recycling of the external water source. Preferably, the external water source 21 in this embodiment can be set at the bottom of the vaporizer 32, so that the sprayed water freely falls after heat exchange with the vaporizer 32 and is collected in the external water source 21. The external water source 21 is placed at the bottom of the vaporizer 32 to directly collect the water passing through the vaporizer 32, realizing the direct recycling of the external water source 21 and reducing the use of pipeline fittings.

[0035] Combined Figure 1 and Figure 2 As shown in the figure, there are multiple spraying pipe fittings 25. Each spraying pipe fitting 25 includes multiple spray pipes 251 connected in parallel. In this embodiment, 3 spray pipes 251 connected in parallel are taken as an example for illustration. The vaporizer 32 includes multiple fins 321 distributed in an array; the multiple fins 321 and the multiple spray pipes 251 are spaced apart.

[0036] The relationship between the multiple spray pipes 251 and the multiple fins 321 is as follows: the multiple fins 321 are distributed in a rectangular shape of m rows * n columns, the multiple spray pipes 251 are distributed in a rectangular shape of (m - 1) rows * (n - 1) columns, and there are 4 fins 321 around the circumference of each spray pipe 251, where m ≥ 4 and n ≥ 4.

[0037] In this embodiment, taking m = 4 and n = 4 as an example for illustration, spray pipes 251 are arranged between every two adjacent rows of fins 321 and between every two adjacent columns of fins 321, so that there is a spray pipe 251 at the centroid of each fin block distributed in a 1*1 rectangle. That is to say, the spray pipes 251 distributed in a 3*3 matrix are arranged at intervals among the fins arranged in a 4*4 matrix. Such an arrangement can maximize the heat exchange efficiency between the sprayed water and the vaporizer, and make full use of each spray pipe 251 to spray water in the circumferential direction.

[0038] As Figure 2 shown, a spray pipes 251 are arranged along the flow direction of liquid nitrogen entering the vaporizer 32, and the number of nozzles 252 on the a spray pipes 251 shows a decreasing trend along the flow direction of liquid nitrogen; where a ≥ 3. Along the flow direction of liquid nitrogen, the energy of the vaporizer decays, and under the sprayed water with constant water temperature, the required water volume gradually decreases. In order to improve the recycling rate of the sprayed water, the number of nozzles shows a decreasing trend along the flow direction of liquid nitrogen; preferably, it decreases in an arithmetic progression. For the liquid nitrogen vaporizer 32, the fins 321 near the inlet along the flow direction of liquid nitrogen have the lowest temperature and require the largest heat exchange amount, while the fins 321 near the outlet have a higher temperature and require a smaller heat exchange amount. Therefore, the number of spray pipe fittings 25 and the water spray volume can decrease in sequence along the flow direction of liquid nitrogen to improve the water spray heat exchange efficiency.

[0039] As Figure 2 shown, in this embodiment, taking 3 spray pipe fittings 25 distributed in parallel as an example for illustration, each spray pipe fitting 25 contains 3 spray pipes 251. According to the flow direction of liquid nitrogen shown by the hollow arrow in the figure, the a spray pipes 251 are divided into 3 groups along the flow direction of liquid nitrogen, and are defined as group A1, group A2, and group A3 in sequence, with the number of each group being a1, a2, and a3 respectively, where a1 = a3 = a / 3, a = a1 + a2 + a3 (when a / 3 is not an integer, it is rounded down); where: a first spray pipe main valve 2541 is provided in group A1, a second spray pipe main valve 2542 is provided in group A2, and a third spray pipe main valve 2543 is provided in group A3. In this embodiment, a1 = a2 = a3 = 1.

[0040] As Figure 4 shown, a plurality of the nozzles 252 are uniformly arranged on the pipe wall of the spray pipe 251, and a pipe plug 253 is provided at the bottom of the spray pipe 251. A plurality of nozzle rings are arranged at intervals in the axial direction of the spray pipe 251, and a plurality of nozzles 252 are arranged at intervals in the circumferential direction of each nozzle ring, ensuring that the spray pipe 251 sprays water onto the fins 321 evenly from top to bottom. The purpose of providing the pipe plug 253 is to control the external water to spray only from the pipe wall of the spray pipe 251 and not leak from the bottom, so that the external water flows from top to bottom and fully continues the heat exchange.

[0041] As Figure 4As shown, the nozzles 252 on the nozzle pipe 251 are distributed in multiple layers axially; the nozzles 252 in the same layer are provided with a plurality of nozzles distributed circumferentially, preferably arranged in an equal-arc annular shape; the opening positions of the nozzles 252 and their water spraying directions are directly opposite to the centers of the fins 321. The purpose of such a setting is to enable the sprayed water from the nozzles to directly reach the fins, reduce the heat energy loss of the sprayed water, directly act on the fins, and improve the heat exchange efficiency.

[0042] In this embodiment, it can be achieved by gradually shortening the length of the nozzle pipe. The nozzle spacing between adjacent two layers on each nozzle pipe is the same, as Figure 4 shown: For the A1 group on the left, each nozzle pipe 251 of the nozzles 252 is provided with 6 layers, with 4 nozzles in each layer; for the A2 group in the middle, each nozzle pipe 251 of the nozzles 252 is provided with 4 layers, with 4 nozzles in each layer; for the A3 group on the right, each nozzle pipe 251 of the nozzles 252 is provided with 2 layers, with 4 nozzles in each layer. Such a setting is to reduce the amount of sprayed water while ensuring the heat exchange efficiency of the sprayed water with the fins.

[0043] Taking the water tank as an external water source to illustrate the working process of this system: When the LNG ship is at the dock for repair, this system is connected to the heat exchanger 11 and the liquid cargo tank 12 on the ship. The water pump 22 starts to work. The water tank is set at the bottom of the vaporizer 32. The water in the water tank is transported through the pipeline 4 to the heat exchanger 11 to cool the terminal device 13. The water and the terminal device 13 conduct heat exchange in the heat exchanger 11. The heated water is transported through the pipeline 4 into the nozzle pipe 251 of the spray pipe fitting and sprayed from the nozzles 252 towards the vaporizer. During this process, the liquid nitrogen in the liquid nitrogen tank 31 passes through the fins 321 of the vaporizer 32. The sprayed water from the nozzles 252 is sprayed in a direction directly opposite to the center of the fins 321 and then conducts heat exchange with the fins 321. After the sprayed water cools down, it freely falls to the water tank located at the bottom of the vaporizer to complete the collection of the sprayed water and is recycled. At the same time, after the vaporizer undergoes heat exchange with the sprayed water, it prevents the generation of white fog and other obstacles to the line of sight around the vaporizer and removes the frost and ice on the fins. After passing through the vaporizer, the liquid nitrogen is phase-changed into nitrogen and is transported through the low-temperature hose 134 to the liquid cargo tank 12 on the ship for inerting operation.

[0044] In addition, this embodiment is also applicable to ships with multiple heat exchangers 11. During operation, when the temperature sensed by the temperature sensor 26 on the return water manifold 24 exceeds the threshold value T4, multiple heat exchangers 11 are connected through multiple water outlet branches 28 and return water branches 29, and the multiple heat exchangers 11 are connected in parallel to the system. Preferably, t4 = 20 °C.

[0045] Embodiment 2

[0046] As Figure 3As shown, the difference between this embodiment and Embodiment 1 lies only in that: a plurality of the fins 321 are distributed in a rectangular pattern of m rows * n columns, a plurality of the nozzles 251 are distributed in a rectangular pattern of (m / 2) rows * (n / 2) columns, and there are 4 fins 321 circumferentially around each nozzle 251, where m ≥ 6 and n ≥ 6; when m or n is odd, (m / 2) rows or (n / 2) columns are rounded up.

[0047] In the embodiment, taking m = 6 and n = 6 as an example for illustration, every two adjacent rows and every two adjacent columns of fins are taken as a group of fins, and a nozzle is arranged in the middle of the group of fins, so that 4 fins 321 and 1 nozzle 251 at their center form a unit group, and the distribution rules of the spray pipe fittings and the vaporizer are constituted by such unit groups distributed in a 3*3 matrix. With such an arrangement, 1 nozzle 251 can spray water on 4 fins 321 simultaneously, and each fin 321 has and only has one nozzle 251 for spraying water, which can ensure the heat exchange efficiency between the sprayed water and the vaporizer 32 while minimizing the number of nozzles 251, saving costs and simplifying the components of this system.

[0048] Embodiment 3

[0049] As Figure 5 shown, the system includes a plurality of external water sources 21, a plurality of vaporizers 32 and a plurality of liquid cargo tanks 12, which are connected to the system in parallel respectively. In this embodiment, each vaporizer 32 is used in combination with the spray pipe fittings 25, and the structures, relative positions and arrangement manners of each vaporizer 32 and each spray pipe fitting 25 are the same as those in Embodiment 1 or Embodiment 2.

[0050] The system further includes a plurality of water outlet spare interfaces 231 arranged on the water outlet pipe manifold 23 and a plurality of water return spare interfaces 241 arranged on the water return pipe manifold 24.

[0051] In this embodiment, two external water sources 21, two vaporizers 32 and two liquid cargo tanks 12 are taken as examples for illustration.

[0052] As Figure 5 shown, a vaporizer and an external water source are arranged vertically to form a circulation component. Two water tanks are respectively connected to the water outlet pipe manifold 23 in parallel through pipes 4, and a water pump 22 and a pipe valve 221 are arranged on each pipe 4. After the water from the external water source 21 passes through the water outlet pipe manifold 23, it is connected to 1 heat exchanger 11 or multiple heat exchangers 11 through one or more water outlet branches 231; the water heated by the heat exchanger 11 is connected to the water return pipe manifold 24 through one or more water return branches 241, and then flows into the spray pipe fittings 25 through two pipes 4 respectively, and is sprayed from the nozzles 252 of the nozzles 251 in a direction facing the center of the fins 321 to perform heat exchange with the fins 321.

[0053] In this embodiment, two vaporizers 32 are respectively connected to the liquid cargo tank 12 on the ship 1 through cryogenic hoses 134 and are connected in parallel to the system. The liquid nitrogen sources of the two vaporizers 32 can be one liquid nitrogen tank 31 or two liquid nitrogen tanks 31, that is, two sets of vaporization systems can be configured in this embodiment.

[0054] When the system is running in this embodiment, when the temperature sensed by the temperature sensor 26 on the return water pipe manifold 24 exceeds the threshold T5, the multiple vaporizers 32 are connected through multiple water outlet standby interfaces 231 and the return water standby interface 241, and the multiple vaporizers 32 are connected in parallel to the system. Preferably, T5 = 50 °C.

[0055] This embodiment is particularly suitable for mobile use. In the actual application process, the external water source and the vaporizer can be set as an integrated up-and-down structure. According to the required amount of water for ship cooling and the required amount of nitrogen for inerting, multiple groups of external water sources and vaporizers are configured to be connected to multiple heat exchangers at different positions on the ship for cooling or to inert multiple liquid cargo tanks.

[0056] Embodiment 4

[0057] A control method for an LNG ship cooling and inerting system is implemented based on the system in Embodiment 1. The system further includes a control panel, and the control panel is signal-connected to the temperature sensor 26 on the water outlet pipe manifold 23; as Figure 2 or Figure 3 shown, when the temperature T of the water outlet pipe manifold 23 reaches the threshold t1, the H mode is triggered, and the nozzles 251 of group A1 are controlled to open for spraying through the first nozzle main valve 2541; when the temperature T of the water outlet pipe manifold 23 reaches the threshold t2, the HH mode is triggered, and the nozzles 251 of group A2 are controlled to open for spraying through the second nozzle main valve 2542; when the temperature T of the water outlet pipe manifold 23 reaches the threshold t3, the HHH mode is triggered, and the nozzles 251 of group A3 are controlled to open for spraying through the third nozzle main valve 2543.

[0058] In this embodiment, the water pump transports external water into the ship for circulating cooling of the heat exchanger. The heat exchanger is used to cool the terminal equipment on the ship. The temperature of the water returning from the outlet of the heat exchanger rises and is cooled and the temperature drops after passing through the fins of the spray vaporizer. The temperature sensor sets the threshold in advance to trigger the temperature mode. Three levels of modes are set, namely the H, HH, and HHH three-level modes. The temperature thresholds corresponding to the three-level modes are t1, t2, and t3 respectively. By controlling the number of nozzles 251 participating in the system, the heat exchange efficiency with the vaporizer 32 is controlled to achieve more precise control.

[0059] Preferably, 40 °C > t3 > t2 > t1 > 10 °C. For example: the threshold t3 = 25 °C, t2 = 18 °C, t1 = 12 °C.

[0060] Example 5

[0061] As Figure 1 shown, this embodiment provides another control method for the LNG ship cooling and inerting system, which is implemented based on the system in Embodiment 1. The control panel is connected to the temperature sensing signal on the return water manifold 24, and the low-temperature mode threshold t4 and the high-temperature mode threshold t5 are set. The system further includes a plurality of water outlet standby interfaces 231 provided on the water outlet manifold 23 and a plurality of water return standby interfaces 241 provided on the water return manifold 24.

[0062] The system further includes a plurality of heat exchangers 11 connected in parallel and a plurality of vaporizers 32 connected in parallel. Each vaporizer 32 is linked with a water outlet standby interface 231, and each heat exchanger 11 is linked with a water return standby interface 241. When the temperature T of the temperature sensor 26 reaches the low-temperature mode threshold t4, the control panel controls the activation of a plurality of water return standby interfaces 241 to connect a plurality of heat exchangers 11 in parallel to the system. When the temperature T of the temperature sensor 26 reaches the high-temperature mode threshold t5, the control panel controls the activation of a plurality of water outlet standby interfaces 231 to connect a plurality of vaporizers 32 in parallel to the system. The number of vaporizers and heat exchangers participating in the system is controlled through the water return standby interface 241 and the water outlet standby interface 231, and precise automatic operation is achieved through signal connection of the control panel. Preferably, t4 = 20 °C and t5 = 50 °C.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the embodiments of the present invention, rather than limitations on the specific implementation manners of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the claims of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. An LNG ship cooling and inerting system, cooperating with a heat exchanger (11), a cargo tank (12) and terminal equipment (13) inside the hull (1), the terminal equipment (13) being connected to the heat exchanger (11), characterized in that: The system includes a spray system and a vaporization system; The vaporization system includes a liquid nitrogen tank (31) and a vaporizer (32). After the liquefied nitrogen in the liquid nitrogen tank (31) is vaporized by the vaporizer (32), it is transported to the cargo tank (12) through a cryogenic hose (134); The spray system includes an external water source (21) and spray pipe fittings (25) connected through a pipeline (4). The water from the external water source (21) flows into a heat exchanger (11) through the pipeline (4) to cool the terminal device (13). After the cooling water is heated, it forms spray water from the spray pipe fittings and sprays towards the vaporizer (32) through the pipeline (4); The spray water is collected in the external water source (21) after exchanging heat with the vaporizer (32), and the water passing through the vaporizer is directly collected to realize the recycling of the external water source (21); There are multiple spray pipe fittings (25). Each of the multiple spray pipe fittings (25) is provided with multiple spray pipes (251), and each of the multiple spray pipes (251) is provided with multiple nozzles (252); the vaporizer (32) includes multiple fins (321); the multiple fins (321) and the multiple spray pipes (251) are spaced apart; the multiple nozzles (252) are evenly arranged on the pipe wall of the spray pipe (251), and a pipe plug (253) is provided at the bottom of the spray pipe (251); The multiple fins (321) are distributed in a rectangular shape of m rows * n columns. The relationship between the multiple spray pipes (251) and the multiple fins (321) is as follows: The multiple spray pipes (251) are distributed in a rectangular shape of m - 1 rows * n - 1 columns. There are 4 fins (321) circumferentially around each spray pipe (251), where m ≥ 4 and n ≥ 4; Alternatively, the multiple spray pipes (251) are distributed in a rectangular shape of m / 2 rows * n / 2 columns. There are 4 fins (321) circumferentially around each spray pipe (251), where m ≥ 6 and n ≥ 6; when m or n is odd, m / 2 rows or n / 2 columns are rounded up.

2. The LNG ship cooling and inerting system according to claim 1, wherein: The nozzles (252) on the spray pipe (251) are distributed in multiple layers axially; the nozzles (252) in the same layer are provided with multiple nozzles distributed circumferentially; the opening position and the water spraying direction of the nozzles (252) are directly opposite to the center of the fins (321).

3. The LNG ship cooling and inerting system according to claim 2, characterized in that: There are a spray pipes (251) arranged along the flow direction of the liquid nitrogen entering the vaporizer (32), and the number of nozzles (252) on the a spray pipes (251) shows a decreasing trend along the liquid nitrogen flow direction; where a ≥ 3.

4. A kind of LNG ship cooling and inerting system according to claim 3, characterized in that: The a spray pipes (251) are divided into 3 groups according to the liquid nitrogen flow direction, and are sequentially defined as group A1, group A2, and group A3. The number of each group is a1, a2, and a3 respectively, where a1 = a3 = a / 3, a = a1 + a2 + a3, and when a / 3 is not an integer, it is rounded down; where: Group A1 is provided with a first nozzle main valve (2541). The nozzles (252) of each nozzle pipe (251) are provided with 6 layers, with 4 nozzles in each layer; Group A2 is provided with a second nozzle main valve (2542). The nozzles (252) of each nozzle pipe (251) are provided with 4 layers, with 4 nozzles in each layer; Group A3 is provided with a third nozzle main valve (2543). The nozzles (252) of each nozzle pipe (251) are provided with 2 layers, with 4 nozzles in each layer.

5. A kind of LNG ship cooling and inerting system according to any one of claims 2 to 4, characterized in that: The spray system further includes a water pump (22) for pumping out the water of an external water source (21), and a water outlet pipe manifold (23) connected to the external water source (21). The water outlet pipe manifold (23) is provided with a plurality of water outlet branches (28), and one or more of the water outlet branches (28) flow into the heat exchanger (11); the spray system further includes a water return pipe manifold (24) for conveying water to the spray pipe fittings. The water return pipe manifold (24) is provided with a plurality of water return branches (29), and one or more of the water return branches (29) communicate with the heat exchanger (11) and then flow into the water return pipe manifold (24); the spray system further includes a first valve (281) provided on the water outlet branch (28), a second valve (291) provided on the water return branch (29), a temperature sensor (26) and a pressure gauge (27); temperature sensors (26) and pressure gauges (27) are provided on both the water outlet pipe manifold (23) and the water return pipe manifold (24).

6. A control method for the LNG ship cooling and inerting system as described in claim 5, characterized in that: The system further includes a control panel, and the control panel is signal-connected to the temperature sensor (26) on the water outlet pipe manifold (23); When the temperature T of the water outlet pipe manifold (23) reaches the threshold value t1, the H mode is triggered, and the nozzle pipes (251) of Group A1 are controlled to open for spraying through the first nozzle main valve (2541); When the temperature T of the water outlet pipe manifold (23) reaches the threshold value t2, the HH mode is triggered, and the nozzle pipes (251) of Group A2 are controlled to open for spraying through the second nozzle main valve (2542); When the temperature T of the water outlet pipe manifold (23) reaches the threshold value t3, the HHH mode is triggered, and the nozzle pipes (251) of Group A3 are controlled to open for spraying through the third nozzle main valve (2543).

7. The control method of an LNG ship cooling and inerting system according to claim 6, characterized in that: 40°C > t3 > t2 > t1 > 10°C.

8. A control method for the LNG ship cooling and inerting system as described in claim 5, characterized in that: The system further includes a plurality of water outlet spare interfaces (231) provided on the water outlet pipe manifold (23) and a plurality of water return spare interfaces (241) provided on the water return pipe manifold (24); the system further includes a plurality of heat exchangers (11) connected in parallel and a plurality of vaporizers (32) connected in parallel; the control panel is also signal-connected to the temperature sensor (26) on the water return pipe manifold (24); a low-temperature mode threshold value t4 and a high-temperature mode threshold value t5 are set; When the temperature T of the temperature sensor (26) reaches the low-temperature mode threshold value t4, the control panel controls to enable a plurality of water outlet branches (28) and water return branches (29), and connect a plurality of heat exchangers (11) in parallel to the system; when the temperature T of the temperature sensor (26) reaches the high-temperature mode threshold value t5, the control panel controls to enable a plurality of water outlet spare interfaces (231) and water return spare interfaces (241), and connect a plurality of vaporizers (32) in parallel to the system.

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